核糖核酸
清脆的
DNA
核糖核蛋白
质粒
生物
噬菌体
遗传学
大肠杆菌
计算生物学
化学
生物物理学
基因
作者
Sabin Mulepati,A. Héroux,Scott Bailey
出处
期刊:Science
[American Association for the Advancement of Science (AAAS)]
日期:2014-09-19
卷期号:345 (6203): 1479-1484
被引量:203
标识
DOI:10.1126/science.1256996
摘要
In prokaryotes, RNA derived from type I and type III CRISPR loci direct large ribonucleoprotein complexes to destroy invading bacteriophage and plasmids. In Escherichia coli, this 405-kilodalton complex is called Cascade. We report the crystal structure of Cascade bound to a single-stranded DNA (ssDNA) target at a resolution of 3.03 angstroms. The structure reveals that the CRISPR RNA and target strands do not form a double helix but instead adopt an underwound ribbon-like structure. This noncanonical structure is facilitated by rotation of every sixth nucleotide out of the RNA-DNA hybrid and is stabilized by the highly interlocked organization of protein subunits. These studies provide insight into both the assembly and the activity of this complex and suggest a mechanism to enforce fidelity of target binding.
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